This invention relates generally to the field of automatic washing machines and more particularly to a control for determining and supplying the minimum quantity of liquid for properly washing specific fabric loads.
One prior art automatic liquid level control uses a spray device to introduce a predetermined amount of washing liquid into a spinning load of fabrics. A collector rib is formed in the tub for collecting a portion of the liquid introduced into the spinning load as a measure of the liquid absorbed by the load. A liquid collection area is built into the tub at either the bottom or outside of the tub and a pressure-sensitive device is attached to the liquid collection area in communication with the collector rib. The contacts of a liquid level switch are preset, or effectively biased, in proportion to the collected liquid according to the requirements of a given load of fabrics.
Several other prior art liquid level control systems are based on sensing agitation torque to indicate the proper liquid level. In one patent disclosure, if the initial minimum liquid level will prevent the agitation torque from exceeding a minimum the machine will wash at that level. Generally, however, with the minimum liquid level the agitator will transmit torque through the load to the basket and tank or tub to close a switch contact which will energize the liquid inlet solenoid through a relay system.
Still another system senses the number of fabric roll-overs per unit of time. When the proper flow and rollover pattern is established for the washing liquid, the sensing means operates to terminate introduction of liquid.